FIELD: electrical engineering.
SUBSTANCE: invention relates to the field of relay protection and automation. Substance: counts of zero-sequence voltage on common buses and counts of zero-sequence currents on each feeder of the distribution electrical network are recorded with a given sampling frequency. Current and voltage signal counts are subjected to a discrete Fourier transform. The event of a single phase to ground fault is recorded on the condition that the first harmonic of the zero component of voltage and/or distortion coefficient of zero sequence voltage exceeds the corresponding setpoint. In the zero sequence voltage spectrum, the number of the greatest higher harmonic of zero sequence voltage exceeding the setpoint level for said harmonic is recorded. For each feeder, the phase shift thereof with respect to the harmonic of zero sequence voltage is recorded. The phase shifts enter the logic block which isolates the feeder wherefor the sign value at the phase angle is opposite with respect to the phase angles of other feeders.
EFFECT: ensured determination of a damaged feeder.
1 cl, 3 dwg
